Stretches of roads or railways or other installations below rocky walls can be endangered by the instability of the wall above. To prevent fragments and portions of a rocky wall from falling onto stretches of road or railway or on the installations below, the rocky wall is consolidated with netting and cables laid on the wall in order to contain it. Said netting and cables are fixed at intervals over the surface of the wall by means of active and/or passive tie rods driven into the wall.
To correctly lay the netting and cables and to position the tie rods in the rocky wall, two methods are currently used. One method consists in the laying of ground supporting structures, such as tubular scaffolding, for the personnel and machinery. The other method makes use of mobile suspended baskets, which move vertically up and down the wall to be consolidated.
Said baskets consist mainly of a parallelepiped metal structure, suspended at the top of the wall to be consolidated by means of supporting cables; the basket is vertically translated up and down the rocky wall by means of cables operated by one or more hoisting elements. The metal structure of the basket is designed to accommodate the personnel assigned to consolidation of the wall, in addition to the machinery and tools, including the material necessary for laying and affixing the netting and cables to the rocky wall and for the performance of the drilling operations.
The known suspended baskets are provided, on the side facing the rocky wall, with sliding blocks or guides designed both to facilitate translation of the basket up and down the rocky wall and to improve the stability of the basket on the rocky wall during the various consolidation operations. These baskets are also provided with a series of extendible pistons used both to facilitate movement and to stabilize the basket. The above baskets have a number of drawbacks that complicate operations for perfect execution of consolidation work and force the operators to perform several vertical translations up and down the wall and to adopt intricate and complicated stratagems, which at times put their own safety at risk.
In addition to these drawbacks, the current baskets expose the operators to harmful effects deriving from the work carried out, dust and noise, and to the risks inherent in the wall itself, collapse and landslides of portions at risk.
The main problem that the known baskets have to overcome is the continuous variation in configuration due to the irregularity of the rocky wall to be consolidated at the various points along the path of the basket.
Another drawback of the known baskets is the difficulty of reaching, even only occasionally and/or temporarily, areas immediately adjacent to the vertical path of the basket without translating the lifting unit installed at the top of the rocky wall. During consolidation of the wall, situations may occur that cannot be predicted in advance and consequently it is not possible to program with absolute certainty the vertical bands covered by the path of the basket unless each path is amply overlapped with the adjacent ones.
A further drawback of the known baskets consists in the difficulty of the basket, during its vertical translation, of overcoming sudden changes in gradient such as parts jutting out, recesses or projections, ledges or niches.